1. FIELD OF THE INVENTION
The present invention relates to an apparatus for powering down SCSI disk drives, and more particularly, to a SCSI controller receiving a power down request and providing an interrupt to the SCSI device driver to initiate power down of the SCSI disk drives.
2. DESCRIPTION OF THE RELATED ART
Most of the smaller computers, including portable, laptop and notebook computers, have the option of being powered by a rechargeable battery. Since a battery has a finite and limited amount of energy, these smaller computers almost invariably include a power down mode to conserve energy. In typical power down schemes, the system BIOS provides complete control over most of the system assets, including the monitor or display, disk drives including floppy and Integrated Drive Electronics (IDE) hard disk drives, the input/output (I/O) devices, the system clock and sometimes even a portion of the power supply itself.
Hard and floppy disk drives are an integral part of a power down management scheme, since the electrical motors and some of the drive circuitry consume a significant amount of energy. The system BIOS usually has complete control over IDE-type disk drives, so that when a power down mode is initiated during periods of inactivity, the motors and part of the power drive circuitry are shut off as controlled by the system BIOS. This is often referred to as spinning down the disk drives.
In order to meet the Energy Star ratings issued by the Environmental Protection Agency, it is considered desirable to apply power down techniques to all levels of professional or personal computer systems, including desktop PCs and server systems. Many of the larger PC systems, particularly the higher end workstation and server systems, require a significant amount of permanent data storage. This data storage need is often achieved with a separate array of small computer system interface (SCSI) disk drives. Up to seven SCSI disk drives may be coupled to a single SCSI bus and controlled by a SCSI controller. An array of SCSI disk drives may also include multiple SCSI buses, where each bus includes multiple SCSI disk drives. The SCSI disk drives consume a considerable amount of power during operation, so that each should be placed in a spun down state to achieve an effective power down scheme. However, SCSI disk drive systems are usually completely independent of the system BIOS, where the system BIOS has no understanding of or control over the SCSI system including the SCSI device driver, controller and bus. Therefore, traditional power down schemes controlled by the system BIOS are simply inadequate to achieve a comprehensive power-down scheme for a computer system including SCSI disk drives.
It is desirable therefore to implement a comprehensive power-down management scheme for a computer system including SCSI disk drives, with the capability to spin down the SCSI disk drives during periods of system inactivity.